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Old 03-04-2016, 06:22   #61
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Re: Water Heater Placement on a 36 Footer

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No, of course it's all wired through the house system.

The alternator puts power into the system so that the inverter can power the immersion heater without flattening the batteries.

A little math:

To raise the temperature of 20 liters of water from 10C to 50C requires roughly 1kW/h of power. This will take roughly 80 minutes with a 750 watt immersion heater.

A 400 amp/hour 12v battery bank contains about 2.5kW/h of usable power. But with Peukert's coefficient, depending on the proportion between the load and the bank capacity, you will not be able to run a heavy load like an immersion heater without flattening it.

Therefore, you need to be feeding the system with power if you're going to draw it off at that rate. A 100 amp alternator might be able to handle such a load.
Ok, so this is where the engine coolant heat comes into it then is it? It heats the water significantly enough to reduce the amount of power needed to be drawn off by the inverter?

And I take it that my question about running the engine when using the inverter (like I do with the windlass) is a 'yes'? It will help reduce the load on the batteries? Is that correct?
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Old 03-04-2016, 06:28   #62
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Re: Water Heater Placement on a 36 Footer

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Originally Posted by Dockhead View Post
No, of course it's all wired through the house system.

The alternator puts power into the system so that the inverter can power the immersion heater without flattening the batteries.

A little math:

To raise the temperature of 20 liters of water from 10C to 50C requires roughly 1kW/h of power. This will take roughly 80 minutes with a 750 watt immersion heater.

A 400 amp/hour 12v battery bank contains about 2.5kW/h of usable power. But with Peukert's coefficient, depending on the proportion between the load and the bank capacity, you will not be able to run a heavy load like an immersion heater without flattening it.

Therefore, you need to be feeding the system with power if you're going to draw it off at that rate. A 100 amp alternator might be able to handle such a load.
And what advantages are there with a 110v over a 240v heater?
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Old 03-04-2016, 07:15   #63
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Re: Water Heater Placement on a 36 Footer

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And what advantages are there with a 110v over a 240v heater?
Wouldn't the question actually be: which inverter do you have on board? Most (no) folks don't have variable alternating current output inverters.
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Old 03-04-2016, 09:11   #64
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Re: Water Heater Placement on a 36 Footer

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And what advantages are there with a 110v over a 240v heater?
You have a choice? The immersion heater would generally be the same voltage the rest of your AC gear.

If you don't have any AC gear, the best voltage is the one which matches the places you plan to spend most time in. Because naturally you will want to use it off shore power most of the time.

In general of course the higher the voltage, the more efficient the transmission of power, but not many people really have a choice.
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Old 03-04-2016, 14:37   #65
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Re: Water Heater Placement on a 36 Footer

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Wouldn't the question actually be: which inverter do you have on board? Most (no) folks don't have variable alternating current output inverters.
I don't have one as yet, so I would need to purchase one.
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Old 03-04-2016, 14:38   #66
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Re: Water Heater Placement on a 36 Footer

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Originally Posted by Dockhead View Post
You have a choice? The immersion heater would generally be the same voltage the rest of your AC gear.

If you don't have any AC gear, the best voltage is the one which matches the places you plan to spend most time in. Because naturally you will want to use it off shore power most of the time.

In general of course the higher the voltage, the more efficient the transmission of power, but not many people really have a choice.
ok, I'm understanding now. Being in Australia I'll stick to 240v then. I thought maybe 110v was less load or something on an inverter etc.
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Old 03-04-2016, 14:54   #67
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Re: Water Heater Placement on a 36 Footer

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ok, I'm understanding now. Being in Australia I'll stick to 240v then. I thought maybe 110v was less load or something on an inverter etc.
240v is less amperage for the same power as 110v, so generally easier on the equipment. Be happy.
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